Add CTL_PROC back

commit eab03ac7 aka
"[PATCH] Get rid of /proc/sys/proc" was good commit except strace(1) compile
breakage it introduced:

	system.c:1581: error: 'CTL_PROC' undeclared here (not in a function)

So, add dummy enum back.
Signed-off-by: Alexey Dobriyan <adobriyan@sw.ru>
Cc: Stephen Hemminger <shemminger@osdl.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/sysctl.h

@@ -62,7 +62,7 @@ enum
 	CTL_KERN=1,		/* General kernel info and control */
 	CTL_VM=2,		/* VM management */
 	CTL_NET=3,		/* Networking */
-	/* was CTL_PROC */
+	CTL_PROC=4,		/* removal breaks strace(1) compilation */
 	CTL_FS=5,		/* Filesystems */
 	CTL_DEBUG=6,		/* Debugging */
 	CTL_DEV=7,		/* Devices */